/*
 * Copyright (c) 2010, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package jakarta.ws.rs;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Binds the value(s) of a HTTP header to a resource method parameter, resource class field, or resource class bean
 * property. A default value can be specified using the {@link DefaultValue} annotation.
 *
 * The type {@code T} of the annotated parameter, field or property must either:
 * <ol>
 * <li>Be a primitive type</li>
 * <li>Have a constructor that accepts a single {@code String} argument</li>
 * <li>Have a static method named {@code valueOf} or {@code fromString} that accepts a single {@code String} argument
 * (see, for example, {@link Integer#valueOf(String)})</li>
 * <li>Have a registered implementation of {@link jakarta.ws.rs.ext.ParamConverterProvider} JAX-RS extension SPI that
 * returns a {@link jakarta.ws.rs.ext.ParamConverter} instance capable of a "from string" conversion for the type.</li>
 * <li>Be {@code List<T>}, {@code Set<T>}, {@code SortedSet<T>} or {@code T[]} array, where {@code T} satisfies 2, 3 or
 * 4 above. The resulting collection is read-only.</li>
 * </ol>
 *
 * <p>
 * If the type is not one of the collection types listed in 5 above and the header parameter is represented by multiple
 * values then the first value (lexically) of the parameter is used.
 * </p>
 *
 * <p>
 * Because injection occurs at object creation time, use of this annotation on resource class fields and bean properties
 * is only supported for the default per-request resource class lifecycle. Resource classes using other lifecycles
 * should only use this annotation on resource method parameters.
 * </p>
 *
 * @author Paul Sandoz
 * @author Marc Hadley
 * @see DefaultValue
 * @see jakarta.ws.rs.core.HttpHeaders
 * @since 1.0
 */
@Target({ ElementType.PARAMETER, ElementType.METHOD, ElementType.FIELD })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface HeaderParam {

    /**
     * Defines the name of the HTTP header whose value will be used to initialize the value of the annotated method
     * argument, class field or bean property. Case insensitive.
     *
     * @return HTTP header name.
     */
    String value();
}
